Happens a lot in black out cases.
It goes like this. It does not involve the media directly. But they know it happens and that is what the Moose keeps reminding them of.
let me lay it out for you.
Cop to witness. ::
You have given us information that could help us identify the killer. We appreciate that very much. This does put you in danger if the killer knows you can help convict him he may try to kill you or people close to you. We can put you in protective custody. Since we can't put you with criminals that would mean solitary confinement. Do you want us to put you in solitary confinement for the duration of this case? Ok Then there is another alternativ. We have had judge XXXX issue an order forbiding you to talk to anyone but law enforcement officers and the prosecuters about this matter. Remember you can not talk to anyone. Including your closest family members about this. The media may try to get you to talk and could reveal information about you if you talk to them. If you talk to the media or anyone about this evidence you will be picked up and held in solitary confinement at the city (county) jail until such time as the case is resloved or you are no longer needed as a witness. Is that understood?
This is a matter of life and death. If you talk to anyone in the media or anyone at all about this in any manner shape or form you may spend months in solitary confinement behind bars... Is that understood? Here is your copy of the judges order. I advise you to read it completely and follow it to the letter. This is a very very serious matter. Do not even discuss it with anyone not even the closest members of your family. Is that understood?
.
That is what is done and it works. If the cops learn something from a witness and they don't yet have a serial killer in custody this is what is done.
Do you have some documentation on this? I'd like to learn more about how this works.